History of Fins used on Surfboards
Until Tom Blake attached a fin to his surfboard in 1935 people spent thousands of years riding waves without a fin. Control of the surfboard was minimal at best and best done by a surfer dragging his foot in the water. A revolutionary change to the way waves could be ridden; the addition of fins to surfboards caught on relatively quickly. By the late 1940’s early 1950’s having an affixed fin to the bottom of a surfboard was the standard. As the scale of innovation derived from adding a fin to the surfboard became apparent people began to experiment with adding more fins, where they placed the fins, changing the shape and changing the size of the fins. Bob Simmons kneeboard keel fins were developed in the 1940’s and mark the birth of two fin surfboards known as twin fins. It wasn’t until the late 60’s and early 70’s that the Twin really became popular, though. In 1980 Simon Anderson design, built and marketed in conjunction with Gary Mcnabb a three fin surfboard called the Thruster. The creation of the Thruster birthed the modern shortboard and high-performance-ultra controlled surfing of today’s surfers. Adding a fourth fin was experimented with shortly after the creation of the thruster but didn’t gain respectability or major adoption until the 2000’s. In today’s, ride anything era you can paddle out at your local break and see people riding boards with no fins, one fin, two fins, three fins, four fins or even five fins. What fin or fins a surfer uses on their board is now a matter of personal choice made by each individual’s surfing style. A surfer must be aware of his own abilities and how his choice of fins will correlate with those abilities to dictate his approach to wave riding.
A single fin is one, usually large fin placed in the center and rear of the board. Single fins act a rudder; similar to and owing their origin to a boat rudder.
A twin fin is two fins place at the sides of the surfboard. The fins are usually placed further forward than the single fin.
A 2+1 fin setup is a twin fin with a third smaller fin placed in the center and back of the board.
A tri-fin is a three fin setup similar to the 2+1 but all fins are the same size. Tri-fins are the standard in high-performance shortboard surfing. Tri-fins allow for the best control but require more/almost constant movement of the board to avoid drag.
A bonzer is a three fin setup, a five fin set up is also common, where a large center fin is accompanied by smaller side fins.
Quad fins have two fins placed on each side of the surfboard. On fin goes roughly where a normal twin fin would be replaced while another fin is placed slightly back from that fin. The further the fin is pushed back the more the board will ride like a tri fin.
Different Parts of the Fin and How they Affect Performance
The height of the fin is measured from the base, where the fin meets the surfboard to the pointy end of the fin. A bigger fin will sit in the water more and provide more stability. A smaller fin will sit in the water less and provide a loose feeling. Small fins will slide more.
The distance from one side of the fin to the other at the point where the fin meets the surfboard is the base width. A wider base will provide more down the line drive while a narrower base will turn easier and tighter.
Rake is the distance of the curved line between the front base of the fin base and the tip of the fin. A board with less rake will have a tighter curve, sit more straight up and have less distance from base to tip. Boards with less rake allow the surfboard to pivot and make tighter turns better. Adding more rake will allow for more drawn out swooping turns.
The angle of the fin in relationship to the base of the surfboard is the cant. Cant is added to fins to compensate for the drag rail to rail angular changes put on fins that places in a straight 90-degree angle with the base of the surfboard. Flex
The outside and the inside of the fin can be shaped, or foiled to make the fin more dynamic to water flow and to force certain parts of the fin in different ways. Fins can have a flat foil, which is exactly how it sounds. A 50/50 foil creates a gentle and smooth curve from the middle of the fin to the outer edges.
A stiffer fin will have instant response while a flexible fin will be very forgiving and may have a delay between placing weight ino the fin and the board responding.
Fin Placement on the Board
Forward or Back
Moving your fins forward is a great way to make your board easier to turn. While moving your back will give you more stability and potentially more drive. Move your fin or fins too far back and you will start to get drag. Traditional longboards put their single fin way back and take advantage of the drag. The extra drag on a traditional longboard keeps the board in the pocket and the nose up while nose-riding.
The angle of the fins in relationship to the center stringer of the surfboard is known as toe. By turning the fins toe in or facing the stringer in the center water is forced across fins when the board is going straight. This force causes the board to turn easier. While the board turns easier if you are not constantly moving the board you will be getting a ton of drag.
Fin Systems (how fins attach to a surfboard)
The future fin system is a modern fin system with fin boxes that allow for multiple different fin setups. Future fins are screwed in with one allen wrench screw on each fin. https://futuresfins.com/en-us/
The FCS fin system is an alternative to the future fin system. FCS fins now use a no screw pop in pop out system that allows you to change your fins without any tools. http://www.surffcs.com/
Bahne boxes are the standard for big center fins. A Bahne box is great for experimenting with your fin placement as it allows a lot of room for moving the fin placement in the box.
Glassed on fins are permanently attached to the bottom of a surfboard. Glassed on fins are put on at the same time the board is glassed and are not removable or changeable.
Different Fin Shapes
When you change the different elements of each fin you end up with fins that look very different from each other. More important than how the fins look they also perform very differently. If you understand how the different elements of a fin will effect performance you can quickly assess a fin’s shape and size in relation to conditions and the surfing you want to do. For example, a keel fin with its wide base large rake is going to provide a great deal of drive but sacrifice pivot and responsiveness.